Military rifles are needed to provide the general populace with military potential. Its really as simple as that.

Whether it is a local sheriff forming a posse to combat organized criminals, an invading army, or a corrupt govt that turns on its own people - there is an ever present need for the civilian populace to be armed.

When it comes to crazies, low cal handguns at close range are every bit as deadly as high powered rifles. Homemade bombs/IEDs are even more deadly. Heavy vehicles, especially those loaded with fuel and/or explosives are yet again even more dangerous.

Even if crazies were denied some access to simple firearms, I am far more afraid of what they would do if forced to get creative.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)